how linux reboot works

From: gopan (gop_kumar_at_hotmail.com)
Date: 03/19/04 

Date: 19 Mar 2004 04:57:29 -0800

Hi,
          In linux, to reboot (warm) the machine, first we switch to
real mode and jump to 0xf000:0xfff0, in real mode this gives the
physical address 0xffff0, but the BIOS is mapped to 0xfffffff0, then
how this work?

I know that when the processor is switched on, address lines A20-A31
are artifitially boosted so that BIOS can be accessed, but this
artifitial boosting lasts only till the CS is changed right? then in
the above case how exactly is the BIOS code accessed ?

 regards,
  
 Gop

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